The present invention relates in general to telecommunication systems and methods for their management, and in particular to methods of managing networks, operating under varying traffic loads and to telecommunication systems in which varying demands for bandwidth are managed effectively.
The ever-growing traffic load in communication networks has been realized for some time as a problem that requires an urgent solution, as the growing traffic loads threatens the collapse these networks. To date, some solutions were suggested to the problem, among which is a solution suggested in IESS-501 (Rev. 3) entitled xe2x80x9cDigital Circuit Multiplication Equipment Specification 32 kbit/s ADPCM with DSI and Facsimile Demodulation/Remodulationxe2x80x9d, 1992. The solution suggested in pp. 27-29 was to decrease the number of bits in the voice channels under overload conditions of the network. When the demand cannot be met by the network, the algorithms will first lose one bit, and then if the demand is still not met, the algorithms may lose a further bit.
Another solution known in the art is a method described in standard G.763 which defines the management of a communication network under varying traffic loads. Essentially, according to this solution a bit is dropped from every algorithm applied in the bearer, and all these dropped bits are collected to a xe2x80x9cbankxe2x80x9d of bits. When the system load increases, the bits available in the bank can be used. However, if the requirement for bits is further increased and exceeds the number of bits available, each algorithm must xe2x80x9ccontributexe2x80x9d a further bit to the xe2x80x9cbankxe2x80x9d. The process continues as described above, until the network requirements are met.
As may be appreciated, these solutions are directed to provide a solution to the overload problems and are not particularly concerned with system efficiency. In other words, the prior art solutions are directed towards ensuring that traffic will be transmitted through the network, even if the transmission is not carried out in the best possible mode.
It is therefore an object of the present invention to provide a method for improving the managing of networks under varying traffic load in synchronous and asynchronous transfer modes, IP networks, IP frame relating networks or any other applicable communication networks.
It is yet another object of the present invention to provide a system and an apparatus capable of managing telecommunication traffic load in accordance with the availability of the system resources.
Other objects of the invention will become apparent as the description of the invention proceeds.
In accordance with the present invention there is provided a method for managing varying traffic load in a telecommunication network, comprising the steps of:
(i) establishing an instantaneous demand for bandwidth at a pre-defined location of the telecommunication network, by calculating a total number of bits, N, required for conveying transmissions by all active channels connected at that pre-defined location of the telecommunication network, wherein the instantaneous demand may arise from more than one type of algorithms, each associated with at least one active channel;
(ii) comparing the total number of bits required, N thus obtained, with a number of bits M available for use in the pre-defined location of the telecommunication network;
(iii) applying a bit rate adjusting mechanism to each one of the algorithms associated with the active channels when the number of bits M available for use in the pre-defined location of the telecommunication network is different from the total number of bits N required by all the active channels; and
(iv) repeating steps (i) to (iii) periodically.
The term xe2x80x9ctelecommunication networkxe2x80x9d as will be used hereinafter, should be understood to encompass the various types of networks known in the art, such as synchronous and asynchronous transfer networks, IP networks, IP frame relaying networks and the like.
The term xe2x80x9calgorithmxe2x80x9d as will be used hereinafter, refers to various types of handling transmission. Such types of transmission encompass demodulation/remodulation, native data transmission, various types of compression, silence (0 bit/s), non-compressible clear channel (64 kbit/s) and the like.
In accordance with the present invention, the bit rate adjusting mechanism is applied when M the number of bits available is different from the total number of bits N required. However, as can be appreciated by a man skilled in the art, for practical purposes such a mechanism is applied, when M is substantially different than N. Furthermore, the convergence method applied while implementing the bit adjusting mechanism is likely to result with updating the number of bits to be allocated for each active channel in a way that the overall number of allocated bits will not be exactly equal to M, the number of bits available, but based on practical considerations, be less than but essentially close to M.
By a first embodiment of the present invention, the method provided is carried out according to the following steps:
(i) establishing a network instantaneous demand for bandwidth by calculating N, the total number of bits required for the operative algorithms in all the active channels connected to the telecommunication network, wherein said network instantaneous demand may arise from more than one type of algorithms;
(ii) comparing N, the total number of bits required thus obtained, with the number of bits, M, available for use in the telecommunication network;
(iii) if the number of bits available for use in the telecommunication network M is smaller than the network instantaneous demand N, the bit rate adjusting mechanism is used for dropping bits from one or more of the operative algorithms, whereas if the number of bits available for use in the telecommunication network M is greater than the network instantaneous demand N, the bit rate adjusting mechanism may be used for adding bits to one or more of the operative algorithms; and
(iv) repeating steps (i) to (iii) periodically.
According to a preferred embodiment of the invention, the bit rate adjusting mechanism is based on the individual load function of each one of the algorithms applied in the active channels, where the individual load function is defined as the number of bits to be transmitted in the telecommunication network per unit of time, under a given value of load. According to the present invention, the load is determined at a pre-defined location in the telecommunication network. Such a pre-defined location can be for example the bearer, a router, a switch or any other critical point in the network. However, the present invention should also be understood to provide a more comprehensive management by managing loads on a network scale or in a part of such a network. Most preferably, the construction of each algorithm load function is based upon the following (i) assuming that when there is no load at the network (the network load value is practically zero) there are no other algorithms competing with the algorithm for which the load function is being constructed, on the availability of the bearer, and (ii) quantifying the significance of that algorithm in the operation of the specific network (i.e. under what value system load, should bits be dropped from this algorithm when taking into account all types of algorithms that are active in the bearer).
To demonstrate the above, let us assume that a load function is to be constructed for a fax algorithm, In one network the load function may be defined as having a constant value of 15 kbit/s (algorithm with Forward Error Correction, xe2x80x9cFECxe2x80x9d) as long as the network load does not exceed a certain value, say v1. Thereafter, the value of the load function drops to 9.6 kibts/s (without FEC). In another network, a similar shift in the function value from 15 kbit/s to 9.6 kbit/s might also take place, but under a different value for the system load, v2. The difference between v1 and v2 is derived from the significance given to having this algorithm with FEC as compared with the significance given to the other algorithms active in the network. In one case, the operator would like to retain the FEC feature at the penalty of dropping bits from other algorithms sooner, whereas in the other case the operating might prefer to drop the FEC bits as soon as a demand for bits is raised in the network.
Some typical examples of processes which comprise bits dropping are:
FAX: FECxe2x86x92NO FEC
ADPCM: 32 kb/sxe2x86x9224 kb/sxe2x86x9216 kb/s
LD-CELP: 16kb/sxe2x86x9212.8 kb/sxe2x86x929.6 kb/s
CS-ACLEP: 8 kb/sxe2x86x926.4 kb/s
In accordance with the present invention, the adjusting mechanism is carried out according to the following iterative procedure:
(i) setting a start value for the network load parameter;
(ii) associating the load function with each one of the algorithms to be used in the network;
(iii) calculating an updated requirement for bandwidth (bits) for each one of the algorithms associated with the active channels, based on the current value of load existing in a pre-defined location of the network and the load function of that algorithm corresponding to that current value of load existing in that pre-defined location in the network;
(iv) summing up all the updated requirements for bandwidth in that pre-defined location;
(v) comparing the sum of all the updated requirements for bandwidth with the overall bandwidth available in that predefined location If there is a difference between the two, setting a new value for the system load in accordance with convergence principles that are known in the art per se;
(vi) repeating steps (iii) to (v) until the chosen convergence criterion is met.
As should be realized by a person skilled in the art, step (ii) of the above procedure, namely associating a load function with each one of the algorithms to be used in the network, is preferably carried out at the initial configuration of the network, and should not be followed every time the above procedure is carried.
According to yet another embodiment of the invention, the method provided allows the user to further manage the varying traffic load by replacing one algorithm with another, depending on the existing load condition. For example, the load function for ADPCM algorithm may be pre-defined so that upon reaching a certain value of load, this algorithm will be replaced with another algorithm, for example such as LD-CELP.
According to still another aspect of the present invention there is provided an apparatus operative in a telecommunication network, which is capable of managing a varying traffic load, and comprising: a processor for calculating the network local load and determining the allocation of available network resources in accordance with the method provided by the present invention, and a bit allocating/de-allocating device.
In accordance with another aspect of the invention there is provided a system for managing varying traffic load in a telecommunication network, comprising at a first of its ends a processor for calculating the network load, a plurality of channels each comprising a receiver and a transmitter, a bit-allocating device and a bearer connecting the first end of the system with a second end thereof. At its second end, the system comprises a bit-deallocating device, a plurality of channels each comprising a receiver and a transmitter and optionally a processor for calculating the network load. In accordance with this embodiment the information arrives from a trunk, typically in an uncompressed state, to the channels connected thereto. Each of the channels transmits the information received, preferably after processing it e.g. by compressing the information, to a bit-allocating device. Also each of the channels transmits to the processor calculating the network load information to allow identification of the algorithm which is currently in use in that particular channel. The latter information allows the processor to determine the instantaneous expected load in the bearer. The bits are arranged in the bit-allocating device according to a pre-defined convention, e.g. from the channel identified with the lowest number to the one nearing the highest identifying number, and are carried forward along the bearer to a second end of the system. At the second end of the system, the information is received at a bit-deallocating device and transmitted therefrom to a plurality of channels connected to that bit-deallocating device. If required, the information thus received, may be further processed (e.g. decompressing a compressed transmission), and transmitted to the trunks connected with each one of these channels. In order to properly distribute the information to the various channels, the system should be provided at its second end with the information regarding the instantaneous value of the load functions applied for the various algorithms, as well as with the information regarding which algorithm is used by each one of the channels. This information may be comprised in the information transmitted in the bearer, but preferably, the system will further comprise at its second end a processor for independently calculating the system load based on the number of channels using each of the algorithms. The advantage of having such a further processor is in eliminating the need to dedicate part of the space available for transmission, to information that can be generated locally, as well as to reduce possible problems occurring due to transmission errors during the retrieval of the transmitted information.